Abstract

In the aureole of the Beinn an Dubhaich granite, forsterite grew with dihedral angles of less than 110° against calcite, but was progressively and variably annealed towards the equilibrium dihedral angle of 165°. New experimental estimates of calcite–calcite–fluid dihedral angles are presented, ranging from 50–90°. The early low angles may be due to rapid olivine growth into a fluid-filled porosity. The preservation of a range of textural states in the Beinn an Dubhaich aureole has the potential to provide information on the kinetics of grain boundary readjustments in metamorphic rocks, which control pore geometry and permeability.